The This Is 40 star sent her first message from the @meganfox account yesterday, admitting that she was a little behind the times.
"I'm incredibly late to the party but I'm here nonetheless, so what now?" she wrote.
Fox is not currently following anyone on Twitter, although she has already picked up over 37,200 subscribers to her account.
The actress's tweeting debut came shortly after an online hoax claimed that she had died, prompting the phrase "RIP Megan Fox" to trend on the website.
She recently became a parent for the first time, welcoming her son Noah with husband Brian Austin Green in September.